Kinetic Hydrate Inhibitor Removal, Recovery and Reuse from Produced Water and Rich MEG Streams

Offentlig prosjektsammendrag

Offshore natural gas flow lines transport multiphase fluids from the wellhead to a processing facility. One of the key challenges is preventing gas hydrates (ice like plugs) formation in the flow lines. Traditionally this risk is mitigated by injecting large volumes of Mono Ethylene Glycol (MEG) into the flow lines. MEG systems are large with numerous components including pipelines for transportation and distribution, storage tanks, and a regeneration system, which are expensive from a CAPEX and OPEX perspective. The high cost of MEG systems is forcing the industry to consider alternatives. One of the alternatives to MEG is the use of low dosage hydrate inhibitors (LDHI). LDHIs include Kinetic Hydrate Inhibitors (KHI) which delay/prevent the nucleation and growth of hydrates and Anti-Agglomerates (AA) which prevent the hydrate particle growth and agglomeration. The major advantage of KHI over MEG is that the volume required is much lower under similar conditions which reduces CAPEX and OPEX. However, KHIs are not regenerated and the most common KHIs are non-biodegradable. Produced water (PW) containing non-biodegradable KHI cannot be released to the environment and must be injected into disposal wells. The KHI polymer may precipitate and reduce injectivity by plugging the pores in an injection well. KHIs also cause process upsets due to polymer precipitation, resulting in increased OPEX and loss of valuable hydrocarbons. An efficient process for extraction and separation of KHI will address the issues detailed. KHI extraction can be achieved by an immiscible extraction fluid that is mixed into the rich MEG (RM) or PW. KHI will partition into the extraction fluid, which can be separated from the RM or PW. NOV Process & Flow Technologies has initiated a joint industry project (JIP) with two operators of oil and gas fields to demonstrate how this process could be brought to an industrial scale. The project is partly funded by the Research Council of Norway.